The present invention relates generally to digital tomosynthesis imaging systems, and more particularly to a portable tomosynthesis system suitable for use in on-sight locations, confined clinical environments, and so forth.
Digital X-ray tomosynthesis is an imaging technique that enables three-dimensional imaging of a patient using a large-area digital detector typically used for conventional (single projection) radiography. In clinical tomosynthesis techniques, a source of X-ray radiation is moved between imaging positions and multiple images are made by casting an X-ray beam on a digital detector. In certain applications, multiple, distributed and static X-ray sources may be used, or movable sources may be displaced in various patterns or trajectories. In certain systems, the detector is also moved during this process. Three-dimensional data is reconstructed in the form of a number of slices through the patient anatomy, each parallel to the detector plane. Tomosynthesis acquisition consists of a number of projections (X-ray exposures) covering an angular range of less than 180°, and typically between 20° and 40°.
Benefits of tomosynthesis imaging are well-known in practice and many applications have been clearly identified in which the technique is preferred over other medical imaging technologies and protocols. However, conventional clinical tomosynthesis systems require that the relative position of the X-ray source and the X-ray detector be known for each of the multiple exposures, so as to permit the appropriate reconstruction of the tomosynthesis slices. Although this may be a relatively straightforward requirement to satisfy in “fixed” digital radiography systems with dedicated mechanical positioners for both the source and the detector, such fixed systems cannot be readily moved or transported.
In certain situations, a “portable” tomosynthesis system would be an invaluable imaging technology. Such situations might include emergency medical applications, such as for rendering medical attention at the scenes of automobile accidents, trauma locations, building and natural disaster scenes, and so forth. In such situations, the person needing medical care normally should not be moved because of the risk of doing further damage to the spine or other tissues, particularly if a vertebral fracture or other internal injury may be present. Whereas a standard X-ray projection image may not be able to ascertain the presence of such fractures, reconstructed slice imaging from a portable tomosynthesis system should have much better capability for detecting the presence of absence of such fractures without moving the patient. Another use for a portable tomosynthesis system may be in small clinical settings where a larger footprint fixed digital radiography system would be impossible to accommodate given the space constraints.
At present, however, such portable tomosynthesis systems are not available. Difficulties in determining positions of the X-ray source and relative positions of the source and detector, among other technical hurdles, have made development and deployment of such systems problematic. There remains a need, however, for improved X-ray tomosynthesis systems that can be made portable and still provide reliable clinical images and data.